Hence the enthalpy flow rate from a facet of boundary will sum over all species (htotal_i)

Again, the total heat transfer rate reported in Report --> Flux panel will be sum of the enthalpy flow rate values over all the facets of boundary.

3. To make things more clear, please go through the attached test case. A simple UDF is created which will calculate these values for a reacting flow case using above formulas and report the flux values in detailed manner.

4. Please follow the steps below to reproduce the results at your end.